The present invention relates generally to protecting direct current (DC) driver circuits from output faults (e.g., short circuits). More particularly, this invention pertains to circuits and methods for output current in response to a short circuit at the output of and LED driver circuit.
Compared to incandescent lamps and fluorescent lamps, light emitting diode (LED) lighting has a longer useful life and superior dimming capability. That is, dimming an LED light source will not affect the life span of the LED light source. Thus, as the cost of LED lighting decreases, LED lighting is becoming the lighting of choice for many applications.
LED light sources are driven by DC driver circuits, usually constant current DC driver circuits. Underwriters' Laboratories (UL) defines a CLASS-2 LED driver circuit as being isolated with a maximum output voltage of 60V and a maximum output current of 8 A at all times. DC driver circuits operating near the UL CLASS-2 limits typically overshoot or even consistently exceed the 8 A current limitation of UL CLASS-2 LED drivers when the output is shorted to simulate an improperly connected load or a properly connected LED light source shorting out at the end of its useful life. Therefore, there is a need for a reliable circuit to effectively control the output current of an LED driver circuit in a manner that conforms to industry standards.